Primary / secondary Fuel Filter discussion

[KWKloeber]

The PRIMARY filter (whether it be a Racor spin-on or 500 series turbine drop-in, or Dahl, etc.) is generally under the head sink and should be a 2 micron. Although Maine Sail recommened against this in boats where you are uncertain of fuel/tank quality.  The SECONDARY filter is the spin-on filter on the engine. This is generally 10-30 microns and can be a variety of brands, not necessarily Racor. Do I have this correct?

They recommend it for marine applications, but not as the primary filter element.

Noah,
Exactly.  Thread de-hijacked also!
"Should be" a 2u is, I think, a YBYC, IIWMB, etc. -- but am interested in Racor's position on this (marine specifically, not other environments.) I had posted the efficiencies of various brand secondary filters on the TW.  But, they can be misleading because being engine-mounted they'll most likely be less than "lab condition" efficient.  By rights, both filters belong off the vibrating engine, but...

k

Jon,
Mea culpa -- sometimes I tend to abbreviate too much.  What I was getting at was -- there's a difference between a 2u primary in a marine environment v a 2u primary in other environments.  So I was surprised that Racor favored 10u primary for that use.  I haven't seen the beta rations for the 10u, so can't say what the "real" efficiency is, discounting Racor's marketing/branding.  Wonder how much better than my secondary filter (82% efficient @ 10u; 98.67% efficient @ 20u.)

I don't think the installation instructions, etc.. are on the TW -- do you have a link to those recommendations and I'll post them with my racor literature so all have them.

Thanks,
k

[Jon W]

I have a PDF of the RACOR position but is 228 kb. Attachments are limited to 200kb. The web address is

https://www.parker.com/literature/Racor/Mobile_The_Micron_Rating.pdf. See page 9 top right

I have attached a PDF from the trawlersforum dated 2006 on the subject as well.

I have another from a guy named Rich H. who appears on many forums regarding this subject. He is viewed as an expert by many. I'll attach that PDF to a reply to this reply again due to the 200kb attachment limit.

FYI - Others may have access into their tank to clean it, but mine has no access ports for this purpose. When removing the filter on the pick up tube in the fuel tank (Critical Upgrade), I could feel crud on the bottom of the tank so I know it's there.

[Jon W]

Here is the second PDF of a Rich H. response from sailboatowners.com.

[KWKloeber]

Thanks for those Jon!   I haven't read thru all but put it on the list.

Looking at the racor paper, it's pretty much what I thought their recommendation was ....
"The exception .......   marine applications where the fuel supply may be cleaner but also may contain water more often."
So they're taking the middle ground but not recommending against 2u for marine  primary.

In your case w/ the crappy fuel tank I can see what you mean.  Unless until it gets cleaned anyway. 

I'm really pretty sure I'm adding a 2nd Racor for a polisher, Valved so I could flip to either one.   On the B list!
Might move the secondary right off of the engine due to the vibration issue -- or do away with it and have a 10u and 2u Racor in line.

kk

[Jon W]

"where fuel may be cleaner..." is the caveat I was referring to. It may always be cleaner until it isn't.

[Jim Hardesty]

I hope someone can explain my ongoing experience with my factory set of filters on my 2001 MKll.  I use a 2 micron Racor filter element, R15s, and a Universal factory filter spin on, or a Wix 33390.  The first filter to plug is the always the factory spin on.  The max engine rpms will start to drop, then if I change the on the engine, spin on, filter the engine will run normal again.  This happens using a variety of filters on the engine, spin on.  Neither filter looks dirty, or to have water in them.  The Racor bowel looks clean.  My logic says that the first filter should get dirty first. Also I think that the Racor 2 micron is much finer filtering than the spin on. 
Now I change the spin on every season and the Racor every 2 seasons. A few times I've had to change filters during the season.   I use 2 or 3 tanks of fuel each seasons.  Seems like not much fuel being filtered to dirty a filter.  I do have confidence that the fuel I buy is clean.
Something just doesn't seem right to me.
Jim

[Ron Hill]

Guys : I know of a MK I owner that removed the engine bracket & filter and moved it before the Racor filter.

He had a course filter of 15 microns first and then a fine 2 micron filter.

Just remember that when engine is installed in the tractor (a dusty, dirtier environment!), it only has the course 15 micron filter !!!

A few thoughts   

[Paulus]

Also a reminder that the electric fuel pump has a filter in it,  but I don't think it measures in microns.  Probably for the big stuff.
Paul

[Stu Jackson]

Now I change the spin on every season and the Racor every 2 seasons. A few times I've had to change filters during the season.   I use 2 or 3 tanks of fuel each seasons.  Seems like not much fuel being filtered to dirty a filter.  I do have confidence that the fuel I buy is clean.
Something just doesn't seem right to me.
Jim

My experience is just the opposite.

[KWKloeber]

Something just doesn't seem right to me.
Jim

Jim,  to confirm - your Racor is plumbed between the tank and the fuel pump, right?  (i.e., the pump is pulling, not pushing fuel thru the Racor.)   If the pump is before the primary, Racor says the pulsating can affect the filter efficiency - i.e., not allow the filter cake to fully develop (the filter cake is part of the filtering.)

kk

[Jim Hardesty]

Ken,
Yes, it's the factory set-up Racor, pump, then spin-on.  I did add a vacuum gauge just after the Racor and get no useful information.  ie. The vacuum is still low when I start to loose RPM's.  Do you think that the Racor is defective?  How can I check?
Jim

[Ron Hill]

All : Just remember that the "filter" in the electric fuel pump is a wire mesh screen that will catch "chunks", too large to be measured in microns!!  That mesh screen is like the screen in the fuel pickup tube.

A thought

[KWKloeber]

All : Just remember that the "filter" in the electric fuel pump is a wire mesh screen that will catch "chunks", too large to be measured in microns!!  That mesh screen is like the screen in the fuel pickup tube.

The Facet screen is 74 micron, OEM p/n 42379 -- or NAPA p/n 610-1086 if anyone's needs replacing.

Cheers
kk

[Paulus]

Like I said "the big stuff".  I did replace the screen on my electric pump 2yrs ago and also bought a spare pump from Napa.   Well covered thread on this web site a few years ago.  Not sure why I did but things are hard to get in the North Channel.
Paul

PS:  Ken, it does get warm in the North Channel, most days 23 to 29 celsius in the summer.  We do use a freezer and refrigeration as I mentioned in a previous thread.

[mainesail]

I hope someone can explain my ongoing experience with my factory set of filters on my 2001 MKll.  I use a 2 micron Racor filter element, R15s, and a Universal factory filter spin on, or a Wix 33390.  The first filter to plug is the always the factory spin on.  The max engine rpms will start to drop, then if I change the on the engine, spin on, filter the engine will run normal again.  This happens using a variety of filters on the engine, spin on.  Neither filter looks dirty, or to have water in them.  The Racor bowel looks clean.  My logic says that the first filter should get dirty first. Also I think that the Racor 2 micron is much finer filtering than the spin on. 
Now I change the spin on every season and the Racor every 2 seasons. A few times I've had to change filters during the season.   I use 2 or 3 tanks of fuel each seasons.  Seems like not much fuel being filtered to dirty a filter.  I do have confidence that the fuel I buy is clean.
Something just doesn't seem right to me.
Jim

Something is wrong with either how it is plumbed or the filter or filter head itself. A 2μm primary should load up well before the secondary even begins to discolor.  You may also have an air leak. Even with really dirty fuel it takes a long while to plug a secondary 15-17μm filter... If you're not pulling a vacuum, you may want to insert a drag needle vac gauge after the secondary temporarily, then the system is not restricted....

Primary filters should ideally be 10μm or even 30μm there is no need for 2μm unless you are running a common rail diesel and it only works the lift pump harder over its life and leads to premature clogging and high vacuum.... 2μm primaries can actually be dangerous because they can plug significantly faster than owners expect. I had one customer nearly loose his boat to a lee shore when his 2μm plugged very unexpectedly up off Cape Breton Island in NS. If you want clean fuel, clean the tank and install a polishing system, you could run this to 2μm if you wanted, and run a 10μm primary.

I know I have repeated this story many times but.....

Having been on a delivery when the engine failed at multiple inopportune times due to a "new", owner stated less than three weeks, 2μm filter I propose that this can be as much of a safety issue as anything. Most boaters really don't know just how clean the fuel tank is. Clean tanks should be a first priority but in certain situations, like this delivery, it's not always possible.

We did this delivery on a Down East style boat that had essentially been used as a floating condo. The fuel was in horrible shape but this delivery was well before commercial tank cleaners existed as a business. The new owner stocked if for the delivery, with a case of 2μm Racor 900 series filters. This guy pretty much bought everything by the case but that is another story....

Long and short is we went through all the 2μm filters in 1/4 of the trip. We stopped and bought some 30μm filters and we made it all the way to Maine, in 4-8 foot seas, on a single 30μm filter. The big diesel engine ran perfectly.